<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <div id="example-1">
        <button v-on:click="greet">Greet</button>
    </div>
    <script>
        var app = new Vue({
            el: "#example-1",
            data: {
                message: "Hello Vue123321"
            },
            methods: {
                greet: function () {
                    alert(this.message)
                }
            }
        })
    </script>
</body>

</html>